Effects of Exogenous H₂O₂ on ROS Metabolism in Nitraria tangutorum Bobr. Leaves Under Salt Stress

Salt stress is a major abiotic stress limiting plant growth and yield. In the present study, the effects of exogenous H₂O₂ on the reactive oxygen species（ROS） metabolism and the antioxidant system in leaves of Nitralia tangutorum Bobr. under salt stress were studied. N. tangutorum seedlings were subjected to 200 mmol·L^-1 NaCl treatment with or without the exogenous application of H₂O₂ for 7 days. The results showed that NaCl stress significantly increased the relative conductivity, the contents of thiobarbituric acid reactive substances（TBARS） and ROS(H₂O₂ and O₂^·-), as well as promoted the activities of antioxidant enzymes including superoxide dismutase（SOD）, peroxidase（POD）, catalase（CAT）, and ascorbate peroxidase（APX） in N. tangutorum leaves. In addition, exogenous H₂O₂ decreased the relative conductivity, the contents of TBARS, H₂O₂ and O₂^·-, while further enhanced the activities of antioxidant enzymes. These results indicated that H₂O₂ effectively alleviated the adverse effects of NaCl stress on N. tangutorum through the regulation of ROS metabolism.